David B. Loope
Paul R. Hanson
Date of this Version
Mahoney, M., 2018. OSL Dating of the Tolleston Beach at Indiana Dunes National Lakeshore and its Implications for Interpreting the Archaeological Record. M. S. Thesis, Department of Earth and Atmospheric Sciences, University of Nebraska-Lincoln, Nebraska, USA.
The puzzling scarcity of archaeological sites on the Tolleston Beach, the most lakeward shoreline complex at Indiana Dunes National Lakeshore, prompted an investigation into the development of these parabolic dunes in an attempt to determine whether the distribution of known archaeological sites is governed by ancient human behaviors, or influenced by its dune setting which can affect site preservation and discoverability. In order to accurately understand patterns of past human occupation, it is important to know the timing and extent of dune reactivation. Specifically, whether it was frequent enough to influence settlement patterns in the past, or if it was extensive enough to disturb archaeological deposits later on. Soil samples collected from shovel test pits and from vibracores on the crests of two compound parabolic dunes were dated using Optically Stimulated Luminescence to refine the chronology of the Tolleston, determine the age of near surface deposits (those accessible to archaeologists using standard field methods), and to evaluate the validity of applying those methods in this environment. An examination of sedimentary structures in the vibracores and the variability within the OSL data demonstrated that, even for the shallowest samples in this study, bioturbation was likely not significant enough to affect the reliability of the OSL ages. The Tolleston dunes were shown to be active around 4 thousand years ago and possibly also around 2 thousand years ago. OSL ages from shovel test pits clustered around the timing of stabilization of the parabolic dunes on the Tolleston, while ages from the deeper vibracore samples represented the earliest stages of their formation. Subsequent dune reactivation appears to have not been substantial enough to place archaeological deposits outside of the reach of standard archaeological methods, essentially validating the use of these methods to inventory cultural resources in this environment. Since the geologic setting does not appear to preclude the archaeologists’ access to potential archaeological resources, the sparse distribution pattern of human occupation on the Tolleston Beach might be better explained by exploring cultural habitation choices of past populations.
Advisors: David B. Loope and Paul R. Hanson